Dormancy of seeds as compared with dormancy of bulbs in tulips

Temperatures below 15 deg C broke tulip seed dormancy, with an optimum around 5 deg. Temperatures above 15 deg increasingly inactivated the effects of a preceding partial chilling, with an optimum around 30 deg. Both actions were quantitative, depending on the level and duration of the temperature and on the genotype of the seed. Temperature effects on seed dormancy are thus very similar to chilling effects on bulbs, but the latter cannot be reversed.